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Publisher/Editor: I. D. Cheek. Sr. aka Or. kigormtis_ _ V2hS: March, 1992

THE WORLD SCANNER REPORT

A Journal of VHF-UHF Scanner Technology S Engineering

SORRY FOR THE DELAY THIS MONTH

A heavy workload fraught with problems galore and with
enumerable distractions resulted in the WSR going to
press late this month. Please accept my apology and
sincere efforts to not let it happen very often. For the
future, let me restate our minimum guarantee of 8-pages
per issue and 10-issues per year. Given our small size
and an ever present need to earn the bread & butter, it
is conceivable that the WSR might not go to press for a
given scheduled month. If this should ever be the case,
we'll simply give up our scheduled bi-month issue of
May-June or Nov-Dec. The bottom line is that a minimum
of 40-pages and five issues will be released each half
year, or an appropriate auto-extension made to affected
subscriptions sufficient to meet the minimum subscription
guarantee. As it is, we try to exceed the minimum for
most issues. The point here is that if you should miss
an issue, relax and don't panic; more than likely it will
either be late OR made up in a bi-month issue. Obviously,
as we grow, we’ll have to become more rigid in scheduling
and planning, and we are preparing for growth right now!

NEW WAY OF COMMUNICATING WITH US HOW AVAILABLE!

We have a rigid and arduous schedule that does not afford
hobby-related chit-chat by phone. Given the nature of my
work: writing and technical labor, I can ill afford to be
unpredictably distracted & jolted out of focus like the
telephone can do. Distraction & lack of focus cause
inferior products. I am loathe to pass off anything less
than my very best. So, it's difficult & almost impossible
for me to be available by telephone. Client business is
not included in this policy, but since I come and go at
all hours, the telephone is just not the BEST for me. I
have long supported MAIL as the best medium of routine
communications. I go overboard to answer all mail, but
even that has become time consuming. So I have devised
another and very unique forum for hobby, business or most
any other need to get in touch with me: a Computer
Bulletin Board, BBS, known as the Hertzian Intercept!

Midnite- 6:00am, Pacific Time: (619) 578-9247

Effective immediately, you can reach my BBS daily between
the hours of midnight - 6:00 am, Pacific times. The phone
number is (619) 578-9247 for ONLY the stated hours. At
other times, this number is for business ONLY and is
connected to an answering service. First time callers to
the BBS have 20-mins to answer the easy log-on questions
and to leave a personal and/or' introductory message. You
won’t have many privileges for the first session, but
approval & upgrade of your security status will normally
be made within 24 hours, after which you'll have 60-mi ns

per day and access to most of the message and file areas.

To access my Hertzian Intercept B8S, you need a computer,
a modem and a telecom or terminal program that is capable
of running the modem to communicate with other computers
via telephone lines. The parameters of my BBS are: 2400,
1200 & 300 baud; 8 data bits; 0 parity, and 1 stop bit
(8N1). When you call the BBS during its active hours my
computer will answer with a CONNECT message followed by a
message saying "Press Escape Twice to Enter the BBS". Do
so and wait 30-sec for the BBS to load after which you'll
be greeted with the name of the BBS and a short list of
questions, mostly technical so my BBS can match the needs
of your computer. After you've completed the
questionnaire and selected a password, you'll be accepted
for 20-mins of limited operations. At that point and if
I were you, I would go straight to the (H)essage area
from the Main Menu and leave me a message. You can snoop
around later if there's time. So press (M) to start the
message base and at the prompt, select (A)rea followed by
a (6) for E-Mail to SysOp. Then select (P)ost A Message
at the next menu, whereupon you'll see a message form
with your name in the FROM: line. Enter SYSOP or my name
(Bill Cheek) on the TO: line, followed by one or two
words for the subject of your message. (Hello; Question;
Business; Help; etc). Then answer (Y)es or (H)o to
Change Anything? after which you'll be presented with a
message screen. Write your message, and when completed,
punch your ENTER, RETURN or Carriage Return key once or
twice to prompt the self-explanatory menu. If all is
well, press (S)ave your message. You can then look
around the BBS for the remaining time left.

One quick way to leave me a message after answering the
questionnaire is to press (L)og Off which will take you
to the closing menu. Select (L)eave Message to SysOp
First which will accomplish the same thing as above,
except that after you’ve saved your message, you'll be
automatically disconnected. It is quick and efficient
that way, however. Unless I am out of town or sick, I
will answer all messages left in either manner within
24-hours. When you call back, you'll see where there is
"mail in your mailbox". Using this BBS is relatively
intuitive and not at all difficult. Even if you are a
greenhorn at computer networking, give it a try.

I am a greenhorn too, and not at all a BBS expert. Since
the Hertzian Intercept is so new and I am so green, you
won’t find a huge library of files or message bases, but
you will find information and a pleasant roundtable which
will grow with time. You will find this a quick, neat
and timely way to communicate with me, whether your need
is business, hobby or just to get acquainted. There will
also be others there who share our interests in radio!

INTERFACE BBS 24-HRS/DAY: (619) 297-7733

ECONOMICAL CELLULAR DATA DECODER NOW AVAILABLE!

NOTE FOR URGENT NEEDS! My BBS will be part-time until I
can get a 3rd phone line put in, which will be another
2-3 months. If my part time hours of midnight to 6:00am
are not convenient, there is a local full-time BBS to
which mine is linked. You can call the INTERFACE BBS at
(619) 297-7733 which operates very much like mine as
described. After you've logged on, go to the MESSAGE
BASE similar to above and select under AREAS, either the
San Diego Scanner Conference, or the San Diego Shortwave
Conference, both of which are direct linked to my BBS.
While these two conferences are public, I receive any
messages left there several times per day. Address any
messages to me as: Bill Cheek. Likewise, any messages I
post there will be available at the INTERFACE BBS several
times a day, which like I said, is open 24-hours a day.

My Hertzian Intercept BBS is a member of the FidoNet, my
address of which is 1:202/719.2 so if you are affiliated
with any local FidoNet BBS's in your area, we can send &
receive semi-private NetMail via that medium as well as
public messages on the Shortwave/Scanner Echo. I am also
on the GEnie Information Service, address "N.CHEEKSR.1".

PRESS RELEASE

A CELLULAR TELEPHONE MONITOR

E-Systems Melpar Div introduced CELLTAP, a versatile,
compact cellular radio monitoring system, in July at the
National Technical Investigators' Association exhibition
held in Washington, D.C.

Designed for law enforcement professionals, the CELLTAP
system is a compact dialed number recorder and monitoring
system, which can be used at a fixed location or as a
battery-powered portable unit. CELLTAP is intended for
monitoring and recording cellular telephone signaling
activity (such as off-hook, on-hook, and dialed numbers)
and for monitoring or recording audio. The CELLTAP
system can exploit multiple cellular channels with
additional PC expansion cards & receivers.

The software supplied with the CELLTAP system provides
user-friendly operation with menu and function key driven
commands. The data collected by the system is stored on
the PC compatible computer's hard disk drive, along with
the time and date in a format appropriate for standard
data base programs. The standard format allows data to
be sorted & analyzed, and then, using the resulting data,
provides the means for an operator-generated report.

The compact size of CELLTAP allows a number of packaging
options. For example, a 2-channel system that includes a
notebook style PC and microcassette recorders fits in a
standard 5-inch briefcase, while a 16-channel system
occupies just 17.5 inches of rack space.

EDITOR'S NOTE: The price of a basic CELLTAP system
without a computer is around $2,500. Now see the next
article for a cellular decoder that's well under $200!

Cellular Mobile Telephone control channel and voice
channel data can now be economically detected, decoded &
displayed with most any kind of a computer that has a
serial port capable of 9600 baud! Decode continuous data
from a control channel as well those "bzzzt's" on the
voice channels: hand-off freqs, power changes, phone
numbers & more! The Digital Data Interpreter (DDI) from
CCS of Milwaukee, Wl, comes as a kit of parts containing
a professionally produced & etched printed circuit board
and all parts to mount thereon. The user provides only a
project box in which to install the completed board; 1C
sockets (recommended but not essential); a power supply
or DC Adaptor and a serial communications cable with a
DB-9 connector on one end for the DDI and an appropriate
DB-9 or DB-25 to match the serial output connector of the
computer. A modem is not necessary but a telecom or
terminal program is required to read, display and store
the decoded cellular data in the computer. A capture
buffer can record and store decoded data for future use.
Such programs include TELIX, PROCOMM, EASYCOM, 121, ASCII
EXPRESS, TO TELECOM, DATALINK, and many, many more.

The DDI connects to a scanner or other cellular receiver
with ease via a mini coax or shielded mic cable. The
shield of the cable goes to receiver ground while the
center conductor connects via a 1-uF capacitor to the
"high" lug of the SQUELCH control in most scanners;
otherwise to the audio output pin of the receiver's NFM
Discriminator chip. The "high” lug of the SQUELCH is
eminently suitable for the PRO-2004/5/6, PRO-34/37 and
PRO-2022, and should also be just fine for most other
scanners. CCS suggests using the EXT SPKR jack for AOR
scanners, specifically the AR-2500 which was the test bed
for the DDI. This is worthless in Realistic scanners for
good reason! The PRO scanners have built-in voice-band
filters in the audio sections which serves to limit out-
of-voice band signals, including CTCSS tones and high
baud rate data signals! Apparently, AOR scanners are not
so well filtered. CCS is investigating this matter of
best installation points and should have current findings
available at time of order or inquiry for information.

The DDI requires two wires for 12-v DC power; two wires
for connection to the scanner and a 9-conductor serial
cable to most any kind of computer with a serial or COMM
port. The DDI runs at 9600 baud, 8-data bits, 0 or no
parity and 1 stop bit (8N1). Assembly of the DDI's PCB
is not difficult, maybe requiring a couple of hours or
so if all parts and materials are on hand. Don't be
concerned about mounting the PCB in a project box until
it has been checked and operated for a while to ensure
proper operation. Most any DC Adaptor rated at 12-volts
@ 100-ma or more will suffice for power needs.

Operation of the DDI is routine, though mastering the
control codes will take a little time. Control of the
DDI is exclusively from the computer's keyboard. The
Operating Guide could be better and more explanatory, but
a little practice will make most aspects perfectly clear.

The DDI has many modes and variances of operation, but
two main or basic modes; control channel data and voice
channel data. It may not be widely known that short data
bursts are sent on voice channels to control some aspects
of the mobile telephone, among these are the handed-off
freqs, power level control, ID & registration codes &
more. Every so often, a short "bzzzt" will be heard on
cellular voice channels. These are the data bursts,
whereas on the control channels, there is almost a
continuous stream of data, too lengthy and varied to
discuss here. Suffice it to say for now that the DDI can
fill a screen with decoded data from a busy control
channel so fast that it can't be read as the data scrolls
off the screen in a continuous stream. One of the more
pertinent uses of the DDI is to find the new frequency
when a cellular conversation is "handed off”. Law
enforcement personnel will appreciate this capability
when a drug dealer is about to announce the drop point as
a frequency hand-off takes place. The new frequency is
decoded from that momentary "bzzzt" and displayed on the
computer’s monitor. As soon as that channel goes dead,
reprogram the scanner with the indicated frequency to
resume unabated monitoring.

The Digital Data Interpreter Kit and instructions are
available from: CCS; PO Box 11191; Milwaukee, HI 53211

CAVEAT: The ECPA of 1986 makes it unlawful to intercept
cellular telephone conversations including computer data
communications, so the DDI probably can be used legally
only by authorized law enforcement, telephone industry
and maintenance personnel. Check with an attorney if in
doubt about the legality of your application.

SCANNER FREQUENCY MANAGEMENT - Part I

by Perry Joseph, President, DataFile Inc.

About the Author: Perry Joseph is a programmer who
specializes in custom database applications. His company,
DataFile, Inc., has recently introduced a frequency
management system for IBM and compatible computers. (See
V1N9P8). In a series of articles, he will discuss his
techniques for frequency management, from simple record
keeping to custom database management and finally, the
creation of ProScan. You can write to Perry in care of
DataFile, P.O. Box 20111, St. Louis, Missouri, 63123 or
through Genie BBS, address "P. Joseph."

Scanning & monitoring the VHF-UHF spectrum can be a
totally consuming hobby at times, but keeping track of
hundreds or thousands of those "nameless numbers" can be
a real chore, and a migraine headache. Well, if yours is
a ten channel scanner, skip the rest of this article; I'd
hate to clue you in on an obscene nightmare.

In my early days of scanning, my monitoring pleasure was
limited by a handful of crystals. Frequency Management,
to me, consisted of a short list typed on a sticker stuck
to the 10-channel radio. No problemo!

Then I stepped up to a 200 channel programmable scanner,
only to learn that new challenges and the obscene
nightmare were created. Forget the sticker scheme! I
got real smart and wrote up a tentative list, entered the
frequencies into the radio and then typed out the final
list while praising the Almighty for having given me the
intestinal fortitude to take Typing 101. This, however,
proved not to be the total solution. And the obscene
nightmare woke me up in a cold sweat.

Programmable scanners offer something crystal radios did
not; the ability to reprogram the radio without having to
open the box and change crystals. In my first year of
owning 200 channels, I changed the frequencies a half
dozen times or more. I edited the original frequency
sheets by crossing out old entries and writing in new
ones, producing a frequency list which looked more like a
crib sheet. Eventually, I had to retype these untidy
lists. The recurring obscene nightmare gave me insomnia.

Aha! I plopped back down in front of the typewriter and
concocted a blank form sheet with the necessary headers
and column lines and then photocopied it for continual
use. Now my mess looked organized. The list always
looked great as long as I didn't change anything. But of
course, changing frequencies on a scanner is about as
synonymous as fish swimming in water. The obscene
nightmare turned ugly.

The advent of programmable scanners produced an anomaly.
Trading frequency lists with other enthusiasts became the
"in thing". Now that we didn't have to buy crystals,
trying out new channels was as easy as punching buttons.
The idea was to exchange each other's frequency lists and
try to pick up on new frequencies. The anomaly occurred
when considerable amounts of time were sucked up as I
pored over others’ lists looking for duplicates and
errors. Using a pencil to check off list entries was
arcane and tedious. On top of that, it was like looking
for a needle in a haystack to locate a specific frequency
in a list of hundreds. My list, organized by channel no,
made it easy to find licensee names when using the list
with the scanner. However, when comparing my list with
others, a lot of drudgery would have been easier if I had
been able to sort my list, say to frequency order, to
match the other guy's. The obscene nightmare offered no
relief in sight.

Then I got he 11-bent-for leather to really get organized.

I got me a stack of 3" x 5" index cards and a card box to
hold them all and set about to create a card for each
channel. Each card represented a single channel and had
detailed data including the frequency number, user name,
type of user, etc. Making sure the channel no. appeared
in the top corner of each card, I could easily flip
through them to find, edit, add or delete a channel
record. I even used tabbed dividers to partition the
cards into sets of twenty. Although this system worked
reasonably well, I could not reorganize the records
without physically shuffling the cards or preparing a
duplicate set of cards in a different order. I also did

not like losing the benefits of a typed list. The card
file system offered better organization but was not as
fast as being able to scan a sheet of paper and my typing
looks much better than my handwriting. By this time, not
only could I see the obscene nightmare, but I began to
taste and smell it, too.

If it weren't for computers (and Bill Cheek showing us
how to put thousands more channels into our scanners), I
would probably still be using the card file system today.
In my next column, I will tell you how I went from card
files to computers and how the obscene nightmare was
beaten into submission.

MODIFYING THE PS-90 SEARCH & STORE MODULE - MOD-23b

By: "Professor Peabody"

EDITOR'S NOTE: The Search & Store Modules were introduced
as MOD-23 in Vol-1 of my Scanner Modification Handbook.
In my opinion, the S & S Modules for the PRO-2004/5/6 by
Key Research Co, are the next best thing to peanut butter
& jelly. The PS-90 SEARCH & STORE module automatically
and hands-off finds & stores into regular channel memory
up to 255 frequencies while you're at work, asleep or on
vacation. MOD-28, the Extended Delay Module, works in
harmony with the Search & Store Modules by eliminating
their greatest weakness; an occasional hangup due to very
short signal bursts which come and go before the Search &
Store cycle can be completed. See my SMH Vol-2 and I VSR
V1N6P7 for the details of that potent improvement to the
SSS modules. Now we continue as "Prof Peabody" does a
little more hacking to his Power Search & Store Module to
eliminate what is perhaps its only other weakness. If
you're not acquainted with Key Research Co and their
products, inquire to: PO Box 846; Cary, NC 27512-0846

400-CH STORAGE FOR THE PS-9*

Hello again scanner fans! This month I bring to you a
modification to a modification. The Key Research Co.
POWER SEARCH & STORE module PS-90 offers unattended
capturing & storage of up to 255 freqs and is one of the
most effective and potent scanner mods around. It is
very popular in the serious scanning community. I have
one which works great, but I thought it was kind of weird
that the PS-90 would only store 255 freqs before it
auto-stopped. Well, this Inquiring Mind checked out the
innards of the PS-90 and found five chips and a bunch of
parts. Four of the chips had the markings obliterated but
one was still readable. It's the only 16-pin chip on the
board; a 40103 CMOS 8 bit Presettable Down Counter. The
PS-90's 8 DIP switches preset the number of channels to
be stored, and when the down-count hits 0, a zero detect
signal is generated to the rest of the circuit and tells
it to stop storing freqs. 2*-1 = 255 for you techies.

The PS-90 module allows a maximum of 255 storage counts
before it shuts down operation. I couldn't see the logic
of 255 channels in a 400-channel scanner like my PRO-2005
so I added another counter for 9 bits to permit a program
of more than 255 channels to be stored: 2»-1 = 511

My PRO-2005/PS-90 can now store up to 511 freqs. What?
Only 400 channels in a block you say? Right on, but my
circuit allows the PS-90 to be programmed for any amount
less than 511 channels, too, including 400 exactly! The
PS-90's operation remains the same otherwise.

Find Pin 1 of the 16-pin 1C and then flip the board over.
Verify Pin 1 again; then cut the trace about 1/8" away
from Pin 1. Remove a slight bit of the trace so a cross
connection is not made. Then fabricate the circuit shown
in Fig-1 on a piece of perf board. If you are half good
and know what you're doing, "dead bug" the new circuit
right on the PS-90 board and use 30-gauge wirewrap wire
to make the circuit connections.

My simple circuit consists of a 4060 Counter and a 74HC00
NAND gate connected into the PS-90 with five wires.
Solder my 5-volt wire to Pin 16 of the 40103. Solder my
ground wire to Pin 8 of the 40103. Solder Pin 8 of my
74HC00 chip to an end lug of the SPDT switch. Solder a
wire from the middle lug of the switch to Pin T of the
40103. Solder a wire from the remaining end lug of the
switch to the cut trace that formerly went to Pin 1 of
the 40103. Solder a wire from Pins 1 & 2 of my 74HC00 to
Pin 9 of the 40103. Don’t forget the 2.2-uF bypass cap
from +5v to ground. I had problems with noise and
glitches on the 5-volt line because there are no bypass
caps on the PS-90 module. While you're at it, I
recommend that you solder a 0.1-uF bypass capacitor
directly to pins 7(-) and 14(+) of each of the other IC’s
on the PS-90. Anything between 0.1-uF and 1.0-uF make
good bypass caps. The SPDT switch is included so you can
switch back to original operation anytime you wish.

To operate the new circuit with the switch in the EXTRA
mode, just consider it a 9th DIP switch with a value of
256. Then program the existing DIP switches to a binary
number of about 144. This will add up (256 + 144) to 400
but you might want to put in a slightly lower number, say
140, to make sure a SEARCH & STORE operation doesn't go
past channel 400 and rewrite over the first few channels
that were already stored. To operate the PS-90 as
designed by the manufacturer, just put the new switch
into the NORM mode and set the DIP switches as desired.
And there you have it; otherwise all other functions of
the S&S module are unchanged. Remember to observe the
polarity of any capacitor that you install if it has
such. Also, use minimum heat when soldering to the ICs
and be quick about it, but don't be nervous; you’ll do
just fine. -Prof. Peabody-

UNIDEN BC-855XLT CELLULAR RESTORATION

NOTE: It is unlawful to intercept cellular telephone
signals. Although the procedure described herein will
restore the missing cellular bands, base and mobile, to
the BC-855XLT, you can receive the CMT base band without
modifiying anything by just tuning the image frequencies
at 21.600 MHz higher than the factory-deleted ranges. On
the BC-855XLT, the image band is 894.010 - 915.600 MHz,
though reception might be a little fuzzy and less clear.

Neither COtQitronics Engineering nor the “WORLD SCANNER
REPORT" assumes responsibility for damages or other
liability resulting from attempting to duplicate this
procedure. It is possible that this modification may
void your warranty.

TOOLS NEEDED: Phillips screwdriver, wire cutters, 1/4 or
1/2 watt resistor, 10-k, a small soldering pencil and
small gauge, rosin core solder.

Disconnect the power cord and with the bottom edge of the
scanner facing you, turn it over on a soft surface to
avoid scratching, and proceed as follows:

1. Remove the five Phillips-head cabinet screws and
carefully separate the cabinet.

2. Grasp the speaker plug (not the wires), and carefully
pull the plug from its socket. Lay the two cabinet
halves side-by-side.

3. Refer to Figure 2 and find the fifth jumper in a row
at the top of the right-hand circuit board. Cut
JV-209 at its midpoint and curl the cut ends apart so
they can not touch anything, including each other.

4. Solder one end of the 10-k resistor to the cathode of

diode D201. Solder the other end of this resistor to

the cut end of JV-209 that's closest to the center

area of the board; do not use excessive heat. If the
jumper comes loose from beneath the board, it will
reattach if you hold it still as the solder cools.

5. Plug in the A/C power cord; turn the scanner ON and

press MANUAL : 880. : ENTER in order. If 880.000

appears in the Display, the effort was a success;

otherwise ERROR will be displayed as usual. The
speaker is disconnected, so audio will not be heard.

6. Snip off and remove excess wire from the resistor
leads; plug the speaker connector back in place;
reassemble the cabinet. If factory service is ever
required, the resistor may be removed and the jumper
lead resoldered.

Technical Discussion: In the simplest analysis, a ground
is connected to the CPU, IC-201 Pin 10, via jumper JV-209
which places a 0-v (low) at Pin 10 to block the cellular
coverage. Clip JV-209 to remove the ground and apply +5v
(high) to Pin 10 via the isolation 10-k resistor to
program the CPU to cover the cellular bands. The cathode
of D-201 is a handy source of +5v.

Referring to tne above cellular restoration procedure,
find the jumper wire immediately to the LEFT of JV-209,
the one that was clipped. This will be JV-208 which also
must be clipped. Solder one end of another 10-k resistor
to the cathode of diode D201. Solder the other end of
this resistor to the cut end of JV-208 that's closest to
the center area of the board; do not use excessive heat.

Test the scanner for memory channels 51-100. Some reports
have it that the unit will be locked up when first turned
on after the memory mod. If so, disconnect the unit from
all power for a short time and try again. No harm will
come from this procedure, and if all else fails, you can
always remove the resistor and resolder the clipped
jumper, JV-208. Please let me know of your results, /be

THE CARPET LOOP 11

A HIGH PERFORMANCE INDOOR SHORTWAVE ANTENNA

by David Moisan

INTRODUCTION: Many shortwave listeners can't put up an
outdoor antenna because of location, infirmity or an
unyielding landlord. These hobbyists have few choices: a
short random wire or an active antenna. Neither choice
is adequate for the serious listener. Active antennas
are expensive, apt to generate as much noise as signal,
and are prone to overload. Random wires are cheap and
easy, but are unpredictable performers. Both subject the
receiver to intermod, spurious signals and other trash.

The Carpet Loop II is an ideal upward step for the SW
listener who wants better than a random wire but not the
risk of an expensive dice roll for an active antenna.
The Carpet Loop II has two components: a tuner and the
antenna loop fashioned from 5-conductor rotator cable
available from Radio Shack. The tuner, a giant
L-network, couples the antenna to the radio.

While NO antenna can give a cheap receiver sensitivity,
selectivity, or dynamic range it never had, the Carpet
Loop II will help you get the last ounce of performance
from your radio. I once used a random wire which had
severe problems with a local AM station on 1230 KHz 2-mi
away. Intermod was all over the 9 to 12 MHz band. With
my Carpet Loop, which then was just the cable, the nasty
interference almost vanished and signals were stronger. I
built the tuner later for even better results. If you’re
an avid SWL stuck in an apartment, the Carpet Loop may be
for you. It's cheap: maybe $25 in parts from Radio Shack
but less if you shop around or dig through your junkbox.
It's an excellent first project for the budding SWL.

CARPET LOOP II PARTS LIST

DOUBLING THE MEMORY CHANNELS IN THE BC-855XLT ??

SI 1 pole 6 position rotary switch RS 275-1386
I cannot swear to this procedure, but an examination of Cl 365 pf variable capacitor (see text)
the schematic diagram suggests that 50-channels in the S2 SPST switch your choice
BC-855XLT may have been deliberately blocked at the 01.2 1N914 silicon switching diodes RS 276-112
factory. A pinout of the CPU shows a 100-ch memory if J]»2 6-position terminal strip RS 274-357
Pin 9 is raised from ground to +5v. It wi 1*1 not be Misc 5-cond rotator cable (see text) RS 15-1201

difficult to gain 50 more channels if this is correct. Metal enclosure, spade lugs, connector, coax cable

HOW THE CARPET LOOP II WORKS: Refer to the drawings in
Figure 3. SI, Cl, and the antenna cable connected to J1
and J2 form a large L-network; when SI is switched
between positions A through F, and Cl's capacitance is
varied, the impedance of the antenna system changes. When

51 and Cl are adjusted for best signal, the impedance
between antenna and receiver is matched. D1 & 02 offer
protection against static discharges and strong signals.
The G position of SI grounds the antenna when not in use.

52 disconnects the ground from the antenna, making the
antenna a random wire.

BUILDING THE TUNER : With the exception of Cl, all parts
for the tuner are readily available from Radio Shack.
Cl, the 365-pF variable capacitor, can be salvaged from
an old radio or purchased from a specialty or general
electronics supply. There are no critical parts in the
tuner; as long as SI has at least six positions, it will
do. D1 and D2 can be most any silicon diode. Select an
enclosure that's big enough to comfortably install all
the components.

The choice for J3, the jack to the receiver, depends on
what connector your radio uses for an external antenna.

I used an SO-239 (RS #278-201); you could also use a TV
antenna terminal strip (RS#274-663).

1) Mount the components on the enclosure you'll be
using--all wiring is point to point. I suggest
mounting J1 and J2 on opposite sides, SI and Cl on
top, and J3 on the other end of the enclosure.

2) Wire SI to J1 and J2. If you use the Radio Shack 2P6T
rotary switch, you'll be using just one of the poles.
The diagram of the back of switch is below:

Pols'

WIRE THE TUNER AS FOLLOWS: If you use Radio Shack's
terminal strip, you will need to drill a hole in the
cabinet to pass the wires through from inside. Use a
rubber grommet to keep the wires from fraying.

SI term

—to—)

J1 term

—tO““>

J2 term

#1 .>

SI ,G

# 6

# 7

# 9

—to—>

J2#10 —>

SI,A

—to—>

#10

The above represents the internal wiring of the switch to
J1 and J1 to J2. The rotator cable antenna wiring from
J1 to J2 is shown in Figure 3 on page 8.

3) Install and wire up Cl. Connect one terminal of Cl to
the P terminal on SI. Connect the other end to J3.
If using an SO-239 or phono jack, connect to the
center conductor. If using screw terminals, connect
to terminal #1 on J3.

4) Connect the G terminal on SI to one lug of S-2.
Connect the other lug of S-2 to the ground shell of J3
or to the ground shield if coax, or to terminal #2 if
screw terminals.

5) Connect D1 and D2 in reverse polarity across the
terminals of J3.

This completes construction of the tuner.

ANTENNA CONSTRUCTION : While other kinds of multiconductor
cable can be used, the best for standard use is the
5-conductor rotator cable mentioned in the parts list.
This cable can easily withstand being stepped on; more
importantly, the cable is easily managed and uniform in
layout which enhances performance. It's also easier to
wire than phone cable.

When routing the cable, start at the receiver and go
around the room—or the house—and back to the radio.
Corners are easily made with this flat cable by folding
the cable at a 90° angle, just like folding paper.

WIRING THE CABLE TO THE TUNER: You should have the two
ends of the cable next to the tuner. Split the wires 2-3
inches; strip the ends and solder spade lugs on all the
wires. With the rotator cable, mark the silver
conductor. Connect the wire to the tuner using Figure 3.

GROUNDING: Run a wire—preferably a large one—from the
ground terminal on the tuner (or a mounting screw on the
SO-239 connector if you're using one) to a suitable
ground such as a cold water pipe; I grounded my tuner
with a short length of RG-58 coax connected to a
baseboard heater via an alligator clip. Connect the tuner
to your receiver; it's ready for use!

USING THE CARPET LOOP II : It's easier to use than to talk
about: Tune the receiver to a desired frequency. Adjust
SI and Cl (or the antenna trimmer on the radio) for
strongest signal. That's it. The Carpet Loop 11 is an
inexpensive, easily built, high performance antenna that
can work in almost all apartments.

FATMAN COMPUTER INTERFACE CORRECTIONS

No serious errors have appeared in the FATMAN computer
interface yet, but there are a few omissions that should
be marked on your back issues for future reference:
V2N1P9: Mark "+5v & Pin 14" at U-10a and draw a ground at
U-10a, Pin 7. V2N1P10: Mark "+5v" by the terminal at
Pins 6 & 16 of U-2d. V2N2P11: Mark "+5v & Pin 14" at
U-11 a and draw a ground at U-11 a, Pin 7. Also: Mark "+5v
& Pin 14" at U-12a and draw a ground at U-12a, Pin 7.
Sorry for any inconvenience caused by these omissions.

Figure 1

400-CH STORAGE CIRCUIT FOR THE PS-918 SEARCH & STORE MODULE

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Figure 2
CELLULAR RESTORATION !
and mavbe DOUBLING THE MEMORY CHANNELS

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*»>** TJT&, '££?£

CONFIDENTIAL SUBSCRIPTION ORDER:

Please print clearly

V2N3

NAME:

STREET:

CITY:

STATE: ZIP:

PHONE:( )

AMT ENCLOSED: $

THE BELOH QUEST I OHS ARE OPTIMAL BUT KILL HELP US HELP M!

Radio Interests? (Put YEARS OF EXPERIENCE in each block that applies)
VHF-UHF Amateur CB Shortwave Professional

Scanning?_Radio?_Radio?_Listening?_Radio?_

Career/Profession

Or Occupation:_

List makes & models of your scanners & other radio equipment:

Describe your technical abilities & interests; use reverse as needed.

M/M/92 SUBSCRIPTION RATES & ORDER BLANC V2N3
USA RATES: (Canada + 19%; Other Foreign +29%-surf or +48%-Air)
HSR BACK ISSUES ONLY USA $$ Check Items

1991 Single copies; your choice: 1 ea $ 4.90 _

1991 (1st 6-mos, Jan-May/Jun) 5 ea $15.90 _

1991 (2nd 6-mos, JuI-Nov/Dec) 5 ea $15.00 _

1991 (1st Year, Jan-Nov/Dec) 19 ea $25.99 _

HSR CURRENT SUBSCRIPTIONS ONLY

1992 Single copies; your choice: 1 ea $ 4.99 _

1992 (Jan-May/June) 6-mos 5 ea $15.99 _

1992 (Jan-Nov/Dec) 1-yr 19 ea $25.99 _

1992-3 (Jan 92-Nov/Dec 93) 2-yr 29 ea $45.99 _

OTHER LITERATURE AVAILABLE

HOBBY RADIO BUYER’S DIRECTORY $14.95 ppd surf _

SCANNER MOD HNDBK, Voi-1: $17.95 + $3.99 S&H _’

SCANNER MOD HNDBK, Vol-2: $17.95 ♦ $3.99 S&H _*

* Canada USj4 SSHl Other Foreign US$5 StHj extra for Air Mail

MAKE REMITTANCE PAYABLE IN US FUNDS TO: CmTmiCS ENGINEERING
Enclose a 119 S.A.S.E. and one loose extra stamp if you want
hobby info & personal reply! Business/trade inquiries exempt.

rrr

EARTH
(SET) DA/T)

Figure 3

CARPET LOOP II - SCHEMATIC & WIRING DIAGRAMS

Aajtea/aiA CAN BE LA/h
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EXTERNAL WIRING- _
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( ANTENNA )

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SILVER

COPPER.

copper.

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copper

CO PPtER

5-/ Postt/oaL

Pos/t/oaj G- is /A SAFETY GROOAJb
Pour I on E /£■ For Hi PEER FREQS,
Positions, D, C , 8 ? A FAR E FOR.
Progressive ln loia/er FPE&S
With Posinou a For lo\Ne st,

ANTENNA CR°TATd/t_CAiBLE) FfGVR£_ TO yf/<?0

COMMTRONICS ENGINEERING
"THE WORLD SCANNER REPORT"
PO BOX 262478
SAN DIEGO, CA 92196-2478

V2N3

920306

IN THIS ISSUE FIRST CLASS HAIL

t New Computer 88S for the "I ORLD SCANNER REPORT" 4 COMMtronics Engineering
Call (SIS) 578-924J Hidnight-6:tt am, Pacific Time ONLY
+ PRESS RELEASE: A Cellular Telephone Monitor
+ Economical Cellular Telephone Data Decoder
t Scanner Frequency Management; Part I
t Modification for the PS-90 Search & Store Module
+ Uniden BC-855XLT Cellular Band Restoration
- + Double the Memory Channels in the BC-855XLT? Maybe
t Carpet Loop 11; a High Performance SWL Antenna
t Error Corrections for FatMan Computer Interface

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